1. Field of the Invention
The present invention generally relates to the field of mobile handset communication. More particularly, this invention relates to improved techniques in the areas of SMS (Short Messaging Service), EMS (Enhanced SMS) and Inage messaging with respect to a GSM (Global System for Mobile Communication) communications network.
2. Description of the Related Art
There are two basic types of services offered through GSM: telephony (also referred to as teleservices) and data (also referred to as bearer services). Telephony services are mainly voice services that provide subscribers with the complete capability (including necessary terminal equipment) to communicate with other subscribers. Data services provide the capacity necessary to transmit appropriate data signals between two access points creating an interface to the network. In addition to normal telephony and emergency calling, GSM supports dual-tone multifrequency (DTMF), facsimile group III, cell broadcast, voice mail, fax mail and short message services (SMS).
The latter of the above-referenced GSM facilities, SMS, is the service most relevant to the present invention. According to the SMS service, a message consisting of a maximum of 160 alphanumeric characters can be sent to or from a mobile station. This service can be viewed as an advanced form of alphanumeric paging with a number of advantages. If the subscriber's mobile unit is powered off or has left the coverage area, the message is stored and offered back to the subscriber when the mobile unit is once again powered on or has reentered the coverage area of the network. This function ensures that the message will be received.
The SMS service makes use of an SMSC (Short Message Service Center), which acts as a store-and-forward system for short messages. The wireless network provides the mechanisms required to find the destination station(s) and transports short messages between the SMSC and wireless stations. In contrast to other existing text-message transmission services, such as alphanumeric paging, the service elements are designed to provide guaranteed delivery of text messages to the destination. Additionally, SMS supports several input mechanisms that allow interconnection with different message sources and destinations.
A distinguishing characteristic of the SMS service is that an active mobile handset is able to receive or submit a short message at any time, independent of whether a voice or data call is in progress. In some implementations, this may depend on the MSC (Mobil Switching Center) or SMSC capabilities. As mentioned above, SMS also guarantees delivery of the short message by the network. Temporary failures due to unavailable receiving stations are identified, and the short message is stored in the SMSC until the destination device becomes available.
SMS is also characterized by out-of-band packet delivery and low-bandwidth message transfer, which results in a highly efficient means for transmitting short bursts of data. Initial applications of SMS focused on eliminating alphanumeric pagers by permitting two-way general-purpose messaging and notification services, primarily for voice mail. As technology and networks evolved, a variety of services have been introduced, including e-mail, fax, paging integration, interactive banking, information services such as stock quotes, and integration with Internet-based applications. Wireless data applications include downloading of SIM (Subscriber Identity Module) cards for activation, debit, profile-editing purposes, wireless points-of-sale (POSs), and other field-service applications such as automatic meter reading, remote sensing, and location-based services. Additionally, integration with the Internet spurred the development of Web-based messaging and other interactive applications such as instant messaging, gaming, and chatting.
One of the most popular ways an SMS message is sent and/or received is via a GSM handset equipped with SMS capabilities. An identification number is first stored in the memory of the handset. This identification number identifies the Mobil Switching Center (MSC) to which each SMS message from that particular handset will be sent for proper distribution to the intended recipient. The identification number only needs to be stored once and each time an SMS message is generated using that handset, the stored number is used for message routing.
After storing the proper MSC identification number, SMS messages are typically created using the GSM handset by manually entering a combination of message text and/or characters by pressing the appropriate keys located either on the handset itself or on an accessory keyboard that can be operably attached to the handset or Personal Digital Assistant (PDA). According to the SMS standard, up to 160 characters can be sent in each SMS message.
Currently, free-hand message creation, i.e., messages drawn freely by the author using symbols, characters, text, pictures or any other desired nomenclature, as opposed to using predetermined keystrokes, such as in conventional SMS messaging, is known with respect to PDAs. However, such devices are quite expensive and complicated when compared to a conventional cellular handset, i.e., 2G or, second generation handsets. In addition to PDAs, there are certain other approaches that permit free-hand message creation. These other approaches, however, typically require additional hardware devices that work in conjunction with cellular handsets and they are unique for each handset. For example, some known devices must connect to the handset's external connector, which is a proprietary connection for each handset. Furthermore, these externally attached modules are both large and expensive.
Also, the devices that allow free-hand message transmission comprise handsets with externally connected modules that are not generic with respect to the handset. This contributes to increased costs, typically making these devices very expensive when compared to the cost of a cellular handset. PDAs, on the other hand, do not require any attachments, but PDAs cannot send free-hand drawn images. Also, PDA devices are expensive when compared to regular second generation cellular handsets. Lastly, entering message data is even more complicated when it is desired to send a message using characters not supported by the keypad of the device, e.g., Chinese characters.